PROGRAMMING:Summation of sequence

Enter a number to find the sum of 1 and this number
###Input format:
A positive integer n, processing to the end of the file.
###Output format:
Find the sum of 1 + 2 + 3... + n.
###Input example:
Here is a set of inputs. For example:
```in
four
```
###Output example:
The corresponding output is given here. For example:
```out
ten
```







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